408 UNGULATA. 



two canines, which are all similar in size and form. There are six 

 molars on each side of each jaw. The lower incisors bite against a 

 callous pad of gum. But, more remarkable than the arrangement of the 

 teeth, is the structure of the stomach in the cud-chewing families. The}) 

 first swallow their food unmasticated, and then bring it up again to chew 

 it. This regurgitation is effected as follows : the stomach is divided 

 into compartments, of which the largest, lying to the left, is called the 

 riiiniH or " paunch," and receives the food. Here it remains soaking for 

 some time, and is then passed into the rcticnhiin or " honey-comb " bag, 

 where it is made into little balls or pellets which are returned to the 

 mouth by a reverse action of the muscles. In the mouth the food is 

 thoroughly chewed and then swallowed a second time, passing not into 

 the paunch, but into the psaltcriuin or " manyplies." From the " many- 

 plies " a wide aperture leads into the abomasusn or fourth stomach, where 

 the gastric juice is secreted, and digestion completed. 



Among the ruminants alone are found animals which possess those 

 appendages that are usually called horns. But these horns are of two 

 distinct kinds. The true Deer bear on their forehead two solid, bony 

 antlers, which, except in the Reindeer, are confined to the males. 

 These antlers are deciduous, and are shed annually ; they increase in 

 size every time they are reproduced. Oxen, sheep, goats, and antelopes 

 have true horns, consisting of a liorny sheath surrounding a central bony 

 axis : these horns are persistent, that is, they are not shed. In the ante- 

 lope, the horns are compact, without cells ; in the goat, ox, and sheep 

 they have cells which communicate with the nose. 



Wallace remarks that the present distribution of the Ungulata is 

 utterly unintelligible without reference to the numerous extinct forms of 

 existing and allied lamilies ; he adds, that we have good evidence that 

 their wide range over the globe is a comparatively recent phenomenon. 

 Tapirs and Llamas have probably not long inhabited South America, 

 while Rhinoceroses and Antelopes were once perhaps unknown in 

 Africa, although abounding in Asia and Europe. Swine are the most 

 ancient types in both hemispheres, and their great hardiness, omnivorous 

 diet, and powers of swimming, have led to their wide distribution. The 

 sheep and goats, on the other hand, are perhaps the most recent develop- 

 ment of the Ungulata, and seem to have arisen in the Northern region 

 of the Eastern hemisphere, when the climate approximated to that which 

 now prex'aiis in the same regions. 



